Sökresultat
Filtrera
Filtyp
Din sökning på "*" gav 537150 sökträffar
Real-World Variability in the Prediction of Intracranial Aneurysm Wall Shear Stress : The 2015 International Aneurysm CFD Challenge
Purpose: Image-based computational fluid dynamics (CFD) is widely used to predict intracranial aneurysm wall shear stress (WSS), particularly with the goal of improving rupture risk assessment. Nevertheless, concern has been expressed over the variability of predicted WSS and inconsistent associations with rupture. Previous challenges, and studies from individual groups, have focused on individual
Hemodynamic impact of abdominal aortic aneurysm stent-graft implantation-induced stenosis
The current study aims to computationally evaluate the hemodynamic impact of a novel sealing mechanism employed by a recently developed endograft (Ovation TriVascular Stent-Graft System) for endovascular aneurysm repair. The exploitation of two inflatable O-rings to achieve sealing may be advantageous in terms of accommodating challenging anatomies, but comes at a price of a marked inflow stenosis
Effect of posture change on the geometric features of the healthy carotid bifurcation
Segmented cross sectional MRI images were used to construct 3D virtual models of the carotid bifurcation in 5 healthy volunteers. Geometric features such as bifurcation angle, planarity angle, asymmetry angle tortuosity and curvature were calculated for the normal head posture and were compared to the equivalent values acquired with the head rotated clockwise by up to 80 degrees. The results obtai
Static and dynamic cardiac modelling : Initial strides and results towards a quantitatively accurate mechanical heart model
Magnetic Resonance Imaging (MRI) has exhibited significant potential for quantifying cardiac function and dysfunction in the mouse. Recent advances in highresolution cardiac MR imaging techniques have contributed to the development of acquisition approaches that allow fast and accurate description of anatomic structures, and accurate surface and finite element (FE) mesh model constructions for stu
Rightward and leftward head rotation influence the geometric features of the healthy carotid bifurcation
Posture changes may influence the geometry and hemodynamics of the carotid bifurcation [1]. As a result, head rotation may cause geometric changes that alter the hemodynamic variables previously cited to correlate with the development of atherosclerosis. Such variables include oscillating wall shear stress (WSS) and particle residence times. Glor et al. [1] had reported changes in the right caroti
Head rotation effects on the flow and hemodynamics of the human carotid bifurcation
The use of realistic anatomic human carotid artery bifurcation (CB) models with a realistic blood waveform leads to physiologically relevant numerical simulations. To study the effects of head posture on the geometry and hemodynamics of the CB, Magnetic resonance imaging (MRI) was used on six healthy volunteers in two different head postures: 1) the supine neutral (N) and 2) the prone with rightwa
Imaging in Vascular Access
This review examines four imaging modalities; ultrasound (US), digital subtraction angiography (DSA), magnetic resonance imaging (MRI) and computed tomography (CT), that have common or potential applications in vascular access (VA). The four modalities are reviewed under their primary uses, techniques, advantages and disadvantages, and future directions that are specific to VA. Currently, US is th
Morphological and hemodynamical alterations in brachial artery and cephalic vein. An image-based study for preoperative assessment for vascular access creation
The current study aims to computationally evaluate the effect of right upper arm position on the geometric and hemodynamic characteristics of the brachial artery (BA) and cephalic vein (CV) and, furthermore, to present in detail the methodology to characterise morphological and hemodynamical healthy vessels. Ten healthy volunteers were analysed in two configurations, the supine (S) and the prone (
Effect of head posture on the healthy human carotid bifurcation hemodynamics
Head and neck postures may cause morphology changes to the geometry of the carotid bifurcation (CB) that alter the low and oscillating wall shear stress (WSS) regions previously reported as important in the development of atherosclerosis. Here the right and left CB were imaged by MRI in two healthy subjects in the neutral head posture with the subject in the supine position and in two other head p
Haemodynamics and Flow Modification Stents for Peripheral Arterial Disease : A Review
Endovascular stents are widely used for the treatment of peripheral arterial disease (PAD). However, the development of in-stent restenosis and downstream PAD progression remain a challenge. Stent revascularisation of PAD causes arterial trauma and introduces abnormal haemodynamics, which initiate complicated biological processes detrimental to the arterial wall. The interaction between stent stru
Effect of head rotation at the prone position on the geometric features of the healthy carotid bifurcation
CFD challenge : Solutions using the commercial finite volume solver, fluent
Credibility and Legitimacy. Challenges to Interdisciplinary Research
The Computational Fluid Dynamics Rupture Challenge 2013--Phase II : Variability of Hemodynamic Simulations in Two Intracranial Aneurysms
With the increased availability of computational resources, the past decade has seen a rise in the use of computational fluid dynamics (CFD) for medical applications. There has been an increase in the application of CFD to attempt to predict the rupture of intracranial aneurysms, however, while many hemodynamic parameters can be obtained from these computations, to date, no consistent methodology
The effect of head rotation on the geometry and hemodynamics of healthy vertebral arteries
The geometric and hemodynamic characteristics of the left and right vertebral arteries (LVA, RVA) of six healthy volunteers were investigated for the supine (S) and the prone position (P) a common sleeping posture with head rotation. MRI images were used to reconstruct the subject specific three-dimensional solid models of the LVA and RVA from the level of the carotid bifurcation to the vertebroba
Variability of computational fluid dynamics solutions for pressure and flow in a giant aneurysm : the ASME 2012 Summer Bioengineering Conference CFD Challenge
Stimulated by a recent controversy regarding pressure drops predicted in a giant aneurysm with a proximal stenosis, the present study sought to assess variability in the prediction of pressures and flow by a wide variety of research groups. In phase I, lumen geometry, flow rates, and fluid properties were specified, leaving each research group to choose their solver, discretization, and solution s
Impact of head rotation on the individualized common carotid flow and carotid bifurcation hemodynamics
This paper aims at evaluating the changes that head rotation poses on morphological and flow characteristics of the carotid bifurcation (CB) and on the distribution of parameters that are regarded as important in atherosclerosis development, such as relative particle residence time (RRT), normalized oscillatory shear index (nOSI), and helicity (HL). Using a subject-specific approach, six healthy v
Head posture influences the geometric and hemodynamic features on the healthy human carotid bifurcation
Atherosclerosis is the third leading cause of morbidity and mortality in the Western world. Low and oscillating wall shear stress (WSS) regions have been previously reported as parameters that correlate with the development of atherosclerosis. In this study we investigated geometric and hemodynamic changes in the carotid bifurcation as a result of posture change. Data from magnetic resonance imagi